Finally a call from Coker Tiire that the wheels are in from Wheel Vintiques Series 52 as ordered a 15x7 last year 6/2024, but changed that today prior to payment to 15x8 SSI.
Not sure if this was a good move as the car came new with SSI's in a 14x7, all 4 corners will be the same 255/60-15 at 27.1 dia. The 27.1" was the diameter I gave Auto Gear
for the speedo gear in the M23 they built for me. If traction becomes an issue, I can increase to a 275/60-15 at 28" in the rear.

Yeah, maybe a lot of tire to push in the front, but this build isn't for the track (just a 47 year old memory coming back to life and inheritance of my mom's DD).

 

Back in the 80s a tire shop mistakenly put a 255-60 on the left front of my 70 Supreme when I was getting 245-60-15s all around. That left front tire rubbed on every turn, which is what alerted me to the issue. I think front suspension height has a lot to do with rubbing or not with that tire size.

 

I ran 255/60-15s on 7"-wide SSIIs on the front of my Vista Cruiser (highest ride height of the Cutlasses) for 20 years. I learned to be careful when turning to go very slow over any surface that would cause one or both front springs to compress.

The problem was that the tread would rub on the wheel arch stainless trim and try to remove it or at least bend it. The side wall would also lightly rub on the anti-sway bar.

Depending on offset, your 8"-wide wheels increase the rubbing on the trim versus 7" because they position the tread 1/2" closer to the trim.

Offset aside, the sidewall will be 1/4" closer to the anti-sway bar. I think that will be only an appearance issue that will probably not cause damage either the tire or the sway bar.

You car ride height being lower than mine will cause more contact with the trim. You may need to always avoid using full wheel lock to preserve your trim.

 

Yeah, I wavered back and forth and still am. At least all four are the same, so I can always use the two tires from up front, in the rear and downsize to a 235 in the front. Diameter difference is 1.00 and that will also depend on the offset of where the 8.00" wheel positions them in front. I really don't want to go beyond the 1.00" drop in diameter between the front and rear.

Thanks for the replies "VC" and "Fun".

 

For a bit of assurance regarding relative tire capacity, the stock G70-14 tire rates 1,620 pounds at 32 psi. The 235/60R15 tire has a maximum load capacity of 1,565 pounds at 35 psi.

That's a tossup on load, but you should keep the pressure 3 psi higher than the door decal calls for.